Blind rivet-type clamping fastener

ABSTRACT

A blind rivet-type clamping fastener includes a deformable sleeve, a drift section insertable into or connectable to the sleeve, and a drilling section. The latter is held on either the sleeve or a drift section so that it can be axially moved towards the free end of the fastener or removed therefrom upon exertion of an axial force onto the drilling section during the setting of the clamping fastener.

BACKGROUND OF THE INVENTION

The invention pertains to a blind rivet-type clamping fastener whichincludes a deformable sleeve part, a drift part which may be insertedinto the sleeve part and cooperates with the same at least during thesetting process, and a drilling part.

One example of a known rivet fastener (German Patent No. C 4,003,373)includes a rivet sleeve as well as a rivet drift which may be insertedinto said rivet sleeve. The rivet sleeve and the rivet drift cooperatewith each other via a thread. The enlarged head stud of the rivet driftis pressed against one end of the sleeve by turning the rivet driftrelative to the rivet sleeve, so that the one end of the sleeve isexpanded. Although such rivet fasteners are able to produce an excellentconnection, the drilling part is still present at the rear side of thefastening point.

According to a different known variation (U.S. Pat. No. A 4,293,258),the drill tip, which is in this particular instance fastened onto therivet sleeve, is also present once the setting process has beenconcluded.

The fact that this is practically always the case with self-drillingrivets is additionally substantiated by a previously disclosedself-drilling rivet (German Patent No. A 2,548,860). This particularrivet is provided with a plate-like drilling part which is constructedas one piece together with a widened head stud of the drift part, which,in other words, means that said drilling part is also present after thesetting of the rivet fastener.

These protruding drilling parts represent a substantial hazard, inparticular if the rear side of such connections is freely accessible.Although the utilization of self-drilling blind rivets substantiallyshortens the setting process and thus also reduces the mounting costs,the problem of injuries due to the protruding drilling parts remains.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a blind rivet-typeclamping fastener of the initially mentioned type with which theadvantages of a self-drilling design may be fully exploited during themounting process, but which eliminates the hazard of injuries due toprotruding drilling parts.

According to the invention, this and other objects are attained by thefact that the drilling part is held such that it may be moved or removedtoward the free end of the clamping fastener by exerting an axial forceduring the setting of said clamping fastener.

The drilling part is sufficiently fastened on the clamping fastenerduring the drilling process, so that the hole required to accommodatethe blind rivet-type clamping fastener may be produced. During the finalsetting of the clamping fastener, which means at the time at which thesleeve part is deformed correspondingly, a movement or removal of thedrilling part is caused due to the exertion of forces in the axialdirection. It is particularly advantageous that the drilling part doesnot have to be removed in a separate operation, but that thedisplacement or removal of the drilling part is facilitated directly bythe setting process.

It is also particularly advantageous that the exertion of an axial forceonto the drilling part may be triggered by the relative axial movementbetween the sleeve part and the drift part during the setting of theclamping fastener. This means that the axial movement between the sleevepart and the drift part during the deformation of the blind rivet-typeclamping fastener is utilized to move or remove the drilling part in theaxial direction. Only this particular measure facilitates that thedrilling part may be removed without requiring an additional mounting ordetaching operation.

The invention suggests that the drilling part is held on the sleeve partand/or the drift part in a nonpositive fashion in the axial directionand in a positive fashion in the rotational direction, whereby thedrilling part is, on the side opposite the drill tip, provided with anapproximately radially oriented stop surface which protrudes into theaxial moving range of the drift part or the sleeve part.

It thus suffices if the drilling part protrudes radially into the movingrange of the drift part or the sleeve part which may be moved relativeto the drilling part in at least a small area in order to cause themovement or removal of the drilling part during the setting process.

Since the drilling part is only used once for producing the hole toaccommodate the blind rivet-type clamping fastener, the mutualconnection between the individual elements does not have to be rigid. Itis solely required that the drilling part is held in such a way that itmay not fall off, which means held in a nonpositive fashion in the axialdirection. A positive retention of the drilling part in the rotationaldirection is naturally required in order to transfer the torque duringthe drilling process.

The drilling part is usually manufactured from a different material thanthe sleeve part and the drift part because the sleeve part consists ofan easily deformable material, for example, aluminum, and the drift partmust, in most instances, consist of a stainless material in order toprevent corrosion on the outer side of the fastening point which isexposed to atmospheric influences. However, the drilling part mustconsist of a hardenable steel, which means a carbon steel, because thedrilling of holes into the substructure would otherwise not be possible.

A preferred application example of the invention suggests that the driftpart consists of a bolt-shaped shaft and a head stud which accommodatesthe drilling part and has a larger diameter than the shaft, and that thedrilling part protrudes radially over the section of the head stud whichis situated directly adjacent to the drilling part over at least aportion of the periphery of the head stud.

Especially with rivet sleeves which are widened radially via the largerhead stud of the drift part, it was established that the inner surfaceof the sleeve part is well set on the head stud after the wideningprocess, so that it is solely required that the drilling part slightlyprotrudes over the section of the head stud of the drift part which issituated directly adjacent to the drilling part in order to exert therequired axial force onto the protruding areas of the drilling part.

A preferred application example of the invention suggests that thedrilling part is constructed as a plate-shaped punched part, wherebyboth lateral borders of the drilling part protrude radially over theadjacent section of the head stud of the drift part. This means that anaxial force is exerted at two diametrically opposite points, so that apossible tilting of the inserted drilling part is effectively prevented,and the proper movement or removal of the drilling part is ensured.

An additional variation of the invention suggests that the head stud isconstructed as a collar which has a diameter that is larger than thediameter of the shaft, and that the end area of the head stud whichdirectly faces the drilling part has a reduced diameter.

It was established that this protruding area of the drilling part doesnot necessarily have to protrude over the outer diameter of the headstud of the drift part. It thus suffices if the section of the head studwhich is situated directly adjacent to the drilling part has acorrespondingly smaller diameter. Although the sleeve part is widened bythe head stud of the drift part, the tensions in the sleeve part lead tothe fact that said sleeve part follows the surface contour of the headstud over a subsequent section of the head stud with reduced diameter,which means that the diameter of the sleeve part is reduced again. Thisvariation also provides a safe possibility to exert axial forces ontothe drilling part in order to move or remove the drilling part in theaxial direction. It is, in this particular variation, advantageous ifthe diameter of the head stud of the drift part approximatelycorresponds with the outer diameter of the sleeve part and thus thediameter drilled, whereby the section of the head stud which is situateddirectly adjacent to the drilling part is smaller than the diameterdrilled.

Such a variation is particularly advantageous for reasons ofmanufacturing technology because the individual diameters may be adaptedto each other without requiring drilling part sections which protrudeexcessively in the lateral direction.

With screws it is generally known to move a threaded tip or drill tip inthe axial direction relative to a screw shaft and remove said tip fromthis screw shaft (British Patents Nos. 865,200 and 585,887). However,this instance does not pertain to a two-part fastener, and it isabsolutely required to remove the drill tip or threaded tip in aseparate mounting or detaching operation.

As far as self-drilling fasteners are concerned, it was, in regard tosuch fasteners, also suggested (German Patent No. C 4,003,374) to fastena plate-shaped cutting part solely by pushing said cutting part onto theshaft, which means the rivet drift, so that retention by only pressfitting suffices. This document also mentions the fact that this measureprovides a possibility to remove the cutting part via a punching orpulling movement after the drilling process is concluded, which, inother words, means that a separate operation is required.

In comparison to the aforementioned solutions, this invention makes itpossible to cause the axial movement or removal of the drilling partsimultaneously with the setting of the blind rivet-type clampingfastener in just one operation.

Additional characteristics and advantages of the invention are, in thefollowing, described in detail with reference to the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a blind rivet-type clamping fastener;

FIG. 2 is a side view of a blind rivet-type clamping fastener;

FIG. 3 is a section of the clamping fastener according to FIGS. 1 and 2during the setting process;

FIG. 4 is a variation of a clamping fastener;

FIG. 5 is a section through the clamping fastener of FIG. 4 shortlybefore the conclusion of the setting process;

FIG. 6 is a sectioned representation of the mutual fastening arrangementbetween the drilling part and the drift part of the clamping fastener;

FIG. 7 is a partially sectioned representation through an additionalvariation of a clamping fastener;

FIG. 8 shows the same clamping fastener of FIG. 7 immediately before theconclusion of the setting process; and

FIG. 9 is a section along line IX--IX in FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The blind rivet-type clamping fastener 1 essentially consists of adeformable sleeve part 2 which may be provided with a stop flange 3, anda drift part 4 which may be inserted into the sleeve part 2 andcooperates with said sleeve part 2 at least during the setting process,whereby the aforementioned arrangement may be realized by differentmeans depending on the type of the blind rivet-type clamping fastener.

It is possible to cause the setting of the clamping fastener solely byaxial drawing of the drift part relative to the sleeve part. Anadditional possibility consists of providing the sleeve part 2 and thedrift part 4 with an inner thread and a corresponding outer thread,whereby the setting is in this particular instance caused by mutualturning, or at least by turning the drift part relative to the sleevepart.

The drilling part 5 is, in this particular variation, constructed as aplate-shaped punched part, but the measures according to the inventionmay also be utilized with a drilling part which has an essentiallycylindrical cross section.

The invention attains the objective to move or remove the drilling part5 during the setting process in the direction of the arrow 6, so thatthe protruding drilling part no longer cooperates with the blindrivet-type clamping fastener after the setting process is concluded. Thedrilling part 5 is for this purpose (as, for example, shown in FIG. 6)held on the sleeve part 2 in a nonpositive fashion in the axialdirection and in a positive fashion in the rotational direction. Thedrilling part 5 engages into a depression 8 arranged on the drift part 4with a corresponding extension 7, whereby the upper lateral sections 9of the drilling part 5 engage into a continuous radial slot 10, so thatthe positive connection ensures that all aforementioned componentsrotate together. It is naturally also possible to use different types ofconnections for the connection between the one part and the drillingpart 5.

The invention suggests that the drilling part 5 is on the side oppositethe drill tip 11 provided with at least one approximately radiallyoriented stop surface 12 which protrudes into the axial moving range ofthe drift part 4 or the sleeve part 2, depending on the fact on whichpart the drilling part 5 is held. An axial force is exerted onto theradially protruding stop surfaces due to the relative movement betweenthe drift part 4 and the sleeve part 2, whereby the aforementionedrelative movement causes a movement or removal of the drilling part 5.Naturally, the stop surfaces 12 must not be oriented exactly radially,which means at a right angle to the central axis of the clampingfastener 1. These stop surfaces may also extend at a correspondinglyacute angle since it is solely required that corresponding stopsurfaces, protruding stop cams, or similar elements are provided. Itwould also be conceivable that only the area forming the stop surfaces12 protrudes radially to the corresponding extent, and that the adjacentarea, or the area between the stop surfaces 12 and the drill tip 11, hasa correspondingly reduced diameter.

In the preferred variation according to FIGS. 1-3, the drift part 4consists of a bolt-shaped shaft 13 and a head stud 14 which has a largerdiameter than the shaft 13 and accommodates the drilling part 5. Thishead stud 14 is, in this particular variation, widened in severalstages. The drilling part 5 protrudes on both sides with the stopsurfaces 12 radially over the section of the head stud 14 situateddirectly adjacent to the drilling part 5. It would suffice if thedrilling part 5 only protrudes radially on one side, but this measurewould be disadvantageous because the drilling part could be tiltedduring the process of removing the drilling part.

If the sleeve part 2 is situated in the hole produced by the drillingpart 5 after the conclusion of the drilling process, and if the driftpart is retracted in the direction of the arrow 15 by means of acorresponding tool, the sleeve part 2 is widened by the penetrating headstud 14 as shown in FIG. 3. However, the sleeve part 2 is always wellset on the surface of the head stud 14 with its inner diameter due tothe internal tensions in the widened sleeve part. After correspondingaxial movement of the drift part 4 in the direction of the arrow 15,namely as a movement relative to the sleeve part 2, the free end area 16of the sleeve part 2 adjoins the stop surfaces 12 of the drilling part 5so that an axial force is exerted onto the drilling part 5 at thislocation. Continued retraction of the drift part causes a movement ofthe drilling part 5 in the direction of the arrow 6 and thus removal ofthe same from the drift part 4. This means that a relatively simpleconstructive measure obtains an optimal effect by facilitating thesimultaneous drilling of a hole, the setting of a blind rivet-typeclamping fastener, and the removal of the drilling part required for theproduction of the hole in just one operation. The drilling part is notonly removed to eliminate the danger of injuries, but also to eliminatethe possibility of corrosion since such drilling parts are usuallymanufactured from a carbon steel.

The design and function of the variations according to FIGS. 4-6 aresimilar to the ones of the variations according to FIGS. 1-3, but thehead stud 14 is constructed as a collar which has a diameter that islarger than the shaft 13. The end area 17 of the head stud whichdirectly faces the drilling part 5 has a reduced diameter. It isadvantageous if the diameter of the head stud 14 approximatelycorresponds with the outer diameter of the sleeve part 2 and thus thediameter drilled, whereby the section 17 of the head stud 14 which issituated directly adjacent to the drilling part 5 is smaller than thediameter drilled. It suffices in this particular variation if thedrilling part 5 with the stop surfaces 12 protrudes radially over atleast the diameter of the section 17 because this sleeve part exactlyfollows the contour of the head stud 14 and also the section 17 duringthe setting and the widening of the sleeve part 2. Due to the internaltensions during the widening process, the sleeve part adapts itself tothe section 17 with a smaller diameter which is situated behind the headstud 14 with a larger diameter, so that the lower end area of the sleevepart 2 again reaches the stop surfaces 12 of the drilling part 5 andremoves the same in the axial direction.

The variations according to FIGS. 7-9 solely differ from the twopreviously described variations by the fact that the drift part 4 has ashaft 13 or a head stud 14 with a cross-sectional shape that isdifferent from the previously described circular shape. These sectionsare, in this particular variation, constructed with a square crosssection. It is naturally also possible to choose any othercross-sectional shape, whereby elevations or grooves which extend inlongitudinal direction and cooperate correspondingly with a surface onthe inner side of the sleeve part may be arranged on the surface of thedrift part. Such a variation is particularly advantageous if the torquefor the drilling process is transferred via the drift part as well asthe sleeve part.

In this variation, corresponding stop surfaces 12 of the drilling part 5also protrude radially over the head stud 14, so that the sleeve partwhich advances along the head stud 14 during the setting process adjoinsthe stop surfaces 12 of the drilling part 5 with its free end 16.

The previous description pertains to application examples in which thedrilling part 5 is held on the drift part that is practically alwayssituated on the inside. However, it would also be conceivable to fastenthe drilling part 5 on the drift part as well as the sleeve part,whereby the aforementioned variation would be particularly advantageousfor the application example according to FIGS. 7-9. An additionalvariation is also obtained if the drilling part 5 is exclusively held onthe sleeve part 2. In a variation in which the sleeve part 2 and thedrift part 4 cooperate via a thread, and in which the drift part travelsaxially inward relative to the sleeve part during the setting process,there exists the possibility to move or remove the drilling part whichis held in the sleeve part in the axial direction.

The measures according to the invention may thus be utilizedindependently from the fact that the setting of a blind rivet-typeclamping fastener is performed by axial drawing or by an axial movementdue to a thread connection.

The measures according to the invention may be utilized with blindrivet-type clamping fasteners consisting of any material, but it must beensured that an axial force is exerted onto the drilling part due to therelative axial movement between the drilling part and either the driftor the sleeve part in order to move and remove said drilling part in theaxial direction.

We claim:
 1. In a blind rivet-type clamping fastener comprising adeformable sleeve part (2), a drift part (4) which can be inserted intothe sleeve part (2) and is connected to the sleeve (5), the improvementcomprising the drilling part (5) being configured as a platelet-shapedpart and being held on at least one of said sleeve part and said driftpart so as to enable said drilling part to be moved or removed toward afree end of the clamping fastener (1) by exerting an axial force (6) onthe drilling part during the setting of said clamping fastener, saiddrift part including a shaft (13) and a head stud (14) having an endsection (17) adjoining and facing said drilling part, said head studhaving a diameter greater than a diameter of said shaft.
 2. Clampingfastener according to claim 1, wherein the exertion of an axial forceonto the drilling part (5) may be caused by a relative axial movementbetween the sleeve part (2) and the drift part (4) during the setting ofthe clamping fastener (1).
 3. Clamping fastener according to claim 1,wherein the drilling part (5) is held on at least one of the sleeve part(2) and the drift part (4) in a nonpositive fashion in an axialdirection and in a positive fashion in a rotational direction, thedrilling part (5) being provided on a side opposite to a drill tip (11)with at least one approximately radially directed stop surface (12)which penetrates into an axial moving range of one of the drift part (4)and the sleeve part (2).
 4. Clamping fastener according to claim 1,wherein the shaft (13) of the drift part (4) is bolt-shaped and the headstud (14) accommodates the drilling part (5), and the drilling part (5)protrudes at least over a part of a periphery of the head stud (14)radially over the section (17) of the head stud which is situateddirectly adjacent to the drilling part (5).
 5. Clamping fasteneraccording to claim 4, wherein the drilling part (5) constructed as aplatelet-shaped punched part has both lateral borders thereof protruderadially over the section (17) of the head stud (14) of the drift part(4) which is situated directly adjacent to the drilling part. 6.Clamping fastener according to claim 4, wherein the head stud (14) isconstructed as a collar which has a larger diameter than the shaft (13),and the end section (17) of the head stud (14) directly faces thedrilling part (5) and has a reduced diameter.
 7. Clamping fasteneraccording to claim 6, wherein the diameter of the head stud (14) of thedrift part (4) approximately corresponds to an outer diameter of thesleeve part (2) and thus also a diameter being drilled, and the section(17) of the head stud (14) which is situated directly adjacent to thedrilling part (5) is smaller in diameter than the diameter beingdrilled.
 8. Clamping fastener according to claim 5, wherein the headstud (14) is constructed as a collar which has a larger diameter thanthe shaft (13), and the end section (17) of the head stud (14) directlyfaces the drilling part (5) and has a reduced diameter.
 9. Ablind-rivet-like clamp fastener, comprising a deformable sleeve part(2), a drift part (4) which can be inserted in the sleeve part (2) andwhich is effectively connected with the sleeve part (2) at least duringthe setting process, and a drilling part (5), which is held on at leastone of the sleeve part and the drift part so that it can be shifted orstripped off by action of a force, which can be triggered by a relativemotion between the sleeve part (2) and the drift part (4) produced bythe setting process of the clamp fastener (1), the drilling part (5)being held non-positively as viewed in an axial direction of thefastener and positively as viewed in a rotational direction of thefastener and having, at a side thereof opposite to a drilling tip (11),an approximately radially aligned stop surface (12) which protrudes intoa range of axial movement of one of the drift part (4) and the sleevepart (2), the drift part (4) having a shaft (13) and a head projection(14) having an adjoining section (17) of a larger diameter than saidshaft, the drilling part (5) being configured as a platelet-shapedstamped part having two side edges protruding radially over theadjoining section (17) of the head projection (14) of the drift part(4).
 10. The clamp fastener of claim 9, wherein the adjoining section(17) is an end region of the head projection (14), which directly facesthe drilling part (5) and is constructed with a tapered diameter. 11.The clamp fastener of claim 10, wherein the diameter of the headprojection (14) of the drift part (4) corresponds approximately to anouter diameter of the sleeve part (2) and thus to a drilling diameter,the section (17) of the head projection (14) immediately adjoining thedrilling part (5), having a diameter which is smaller than that of thedrilling part.